The FBI arrested a man on his way to the US Capitol for what he thought would be a suicide attack.REUTERS

WASHINGTON — Authorities today arrested a man on his way to the US Capitol for what he thought would be a suicide attack on one of the nation’s most symbolic landmarks.

Amine El Khalifi, a 29-year-old of Moroccan descent, was nabbed around noon local time following an investigation conducted by the FBI and the US Capitol Police, FOX News reported.

El Khalifi appeared in federal court before US Magistrate Judge T. Rawles Jones Jr. later in the day and was charged with attempting to use a weapon of mass destruction against property owned by the US government.

He faces life in prison if convicted.

El Khalifi was wearing a green T-shirt in court and had a large tattoo on his forearm. Observers in the courtroom said he had a short beard and was very muscular.

Authorities began monitoring El Khalifi in December after he told an undercover law enforcement officer of his plan to conduct an attack on a building containing US military offices in Alexandria, Va.

“The arrest was the culmination of an undercover operation during which the suspect was closely monitored by law enforcement,” the Justice Department said in a statement, adding that the arrest occurred in Washington, D.C.

A short time before the arrest, he had been praying at a mosque in the Washington area.

El Khalifi, who has lived in the US for at least the past 12 years, is not a US citizen and was living in the country illegally, the Justice Department said.

Authorities told FOX News that El Khalifi considered attacking military installations, synagogues and a D.C. restaurant frequented by the military but ultimately settled on a plan to suicide bomb the US Capitol.

El Khalifi thought undercover FBI agents assisting him in his plot were associates of al Qaeda. The FBI also provided the suspect with a disabled gun during the investigation.

When he was arrested Friday, the Moroccan citizen was carrying a vest with him that he thought was packed with explosives, though the material inside was not actually dangerous, FOX News was told.

In preparation for his attack, El Khalifi acquired materials to be used in an improvised explosive device (IED), including a cell phone, jackets, nails and glue, sources said.

Perhaps most worrisome, the 29-year-old traveled to a quarry to participate in an IED demonstration and also conducted surveillance on the Capitol.

Authorities said El Khalifi was never close to carrying out an attack.

“This arrest was the culmination of a lengthy and extensive operation during which the individual was closely and carefully monitored,” US Capitol Police said in a statement. “At no time was the public or Congressional community in any danger.”

Sources told FOX News that congressional leaders were briefed about the arrest, but Senate Majority Leader Harry Reid (D-Nev.) said he had been given no information about El Khalifi.

El Khalifi’s former landlord told The Washington Post Friday that he first reported his tenant’s suspicious behavior over a year ago.

The landlord, retired patent attorney Franky Dynda, said he originally rented the Arlington, Va., apartment to a Bulgarian woman who said she was married to El Khalifi. The woman mysteriously disappeared and El Khalifi stopped paying rent.

El Khalifi was eventually evicted, but in the meantime Dynda said his tenant’s behavior was odd.

“He was suspicious,” Dynda told The Post. “He was getting mysterious packages labeled ‘book,’ but I didn’t think there were books in them.”

Dynda also said El Khalifi’s friends threatened “to beat the hell out of” him when he took him to court to enforce the eviction.

Police on Friday also raided a home in Arlington, Va., based on information obtained investigating El Khalifi.

Authorities told FOX News that they believe El Khalifi was acting alone and the raid of the Arlington home was a separate investigation not part of the inquiry into the plot to blow up the Capitol.